Safety device for water supply networks



Nov. 17, 1953 L. c. E. FRAGER 2,559,383

SAFETY DEVICE FOR WATER SUPPLY NETWORKS Filed Aug. 7, 1947 4 Sheets-Sheet 1 INVENTOR L. C. E. Froger BY WM ay fif I $13 4 ATTORNEYS Nov. 17, 1953 1.. c. E. FRAGER 2,659,383

SAFETY DEVICE FOR WATER SUPPLY NETWORKS Filed Aug. 7, 1947 4 Sheets-Sheet 2 FIG.2.

J INVENTOR L. Q E. Froger ATTORNEYS Nov. 17, 1953 L. c. E. FRAGER SAFETY DEVICE FOR WATER SUPPLY NETWORKS Filed Aug. 7, 1947 4 Sheets-Sheet 3 mm w Q ERE? .H m

INVENTOR L. (l E. FrOger ATTORNEYS Nov. 17, 1953 L. c. E. FRAGER 2,659,383

SAFETY DEVICE FOR WATER SUPPLY NETWORKS Filed Aug. 7, 1947 4 Sheets-Sheet 4 INVENIOR L. C. E. Fruger ATTORNEYS Patented Nov. 17, 1953 UNITED STATES PATENT OFFICE SAFETY DEVICE FOR -WATER SUPPLY NETWORKS Louis Charles Eugene Frager, Paris, France Application August 7, 1947, Serial No. 767,273

' In France July 6, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires July 6, 1964 in case of rupture, cutting off the flow of water in the damaged pipe.

These water-main valves may be operated through automatic control servomotors set in action through either excessive pressure drop or excessive waterflow.

These known systems are generally based on the principle of apparatus actuated in accordance with an appropriate physical quantity. The apparatus sets the controls of an automatic valve in closing position as soon as a predetermined value of the physica1 quantityhas been reached.

When the physical quantity utilized is the rate of flow in the water main, an undesirable closingofi might occur because of a high rate of flow under normal service conditions since a high rate of flow might occur daily and'also in different seasons or due to an increase in population in the water mains area. Furthermore if a break occurs, a great amount of water might run away before the predetermined value of rate of flow has been reached.

When the predetermined physical quantity is the pressure in the main, most of these same drawbacks are present and aggravated through variations of flow of water in the feeding reservoir and this is worse if the automatic valve. is located in a high place and the upstream length of the main is greater. The frequency of inopportune closing-offs can be prohibitive under such conditions.

Furthermore, systems in which motion of the closing-controls of the automatic valve is obtained through swift pressure variations'might close off without necessity the automatic valves of uninjured mains and cause additional unnecessary inconvenience to customers as well as to water supply companies.

In a system where water mains are connected together in any number and one of these mains breaks, the pressure head decreases swiftly not only on the broken main but also on all the other mains and all the respective automatic valves will close at the same time.

The hereafter described system has as its object to avoid these drawbacks. It is essentially based on the use either of the time derivative of a function of the rate of flow or of the time derivative of a function of both the rate of flow and the pressure head, that is to say, on the derivatives of both these two functions and then two time derivatives as predetermined quantities for closing off.

Such a system has the advantage of setting controls in closing position in such a manner that the broken main only is placed out of service and as soon as break occurs.

With the above and other objects in view as will become apparentfrom the detailed description below a preferred embodiment of the invention is shown in the drawings in which:

Fig. 1 is a diagrammatic view of one form-of the invention;

Fig. 2- is a modified type of construction shown diagrammatically;

Fig. 3 is a, plan view of a detail;

Fig. 4 is a plan view of another detail;

Fig. 5 is a diagrammatic view of some further details of the invention;

Fig. 6 is a diagrammatic view of a further modification particularly adapted for emergency use;

Fig. 7 is a diagrammatic view of a detail; and

Fig. 8 illustrates diagrammatically a further modification of the invention particularly designed for a system in which Venturi pipes are used.

Throughout the drawings similar reference characters are used for like parts.

In the present invention the arrangement for releasing the valves so that they move to closed position is subject to the action of a force which is a function of the quotient 2 wherein 10 indicates the pressure in the main and q represents the square of the flow in such main. In accordance with the invention this force will only come into action to bring about the closing of the Valves whenever there is a relatively rapid variation in the pressure or in the resistance to the flow of water in the main.

Therefore, the valves are controlled for the closing thereof only when the two following conditions are fulfilled simultaneously:

1. Whenever the ratio l indicates a relatively important decrease in p or increase in q 2. Whenever there is a rapid variation in the resistance offered to the waterflow through the main considered. I

Only when these two conditions aremet will the safety valve close under abnormal conditions.

In accordance with the invention use is made oftwo pistons wherein one is set into action by motion of the toothed rack is relatively the pressure p prevailing and the other by the square of the flow q in the main. The movements of such pistons is coordinated so that the resulting action is a function of the ratio The above two pistons are preferably coupled by a rotary device whose angular position varies when the ratio of the forces acting upon such pistons varies. The rotary coupling between the two pistons actuates preferably a toothed rack which in turn is connected to another piston which may reciprocate along its longitudinal axis in a movable cylinder which is submitted itself to the action of a spring actuating the said cylinder back to its rest position. If the motion'of the toothed rack is rapid then the piston fixed thereto will displace its cylinder in spite of the spring action so as to release. However, if the slow then the oil inside the cylinder, controlled by the toothed rack, may travel from one side to the other of the piston through a bypass having adjustable throttling means. In such case the water main valve control means are not released.

Furthermore, the invention contemplates a retarding device located on the piston which is actuated by the pressure prevailing in the water main. Such a device may be constructed as a throttle valve placed on the pipe connecting the active face of the above piston to the main and an elastic connection between the piston and the movable element that it operates or by a resilient mounting for the support of the cylinder containing the piston.

in its lower part to the same pressure and in its upper part to the pressure existing in a Pitot tube 53. The pistons 43 and 44 in the cylinders 3 and 13 are mechanically coupled by means of the rotary system l2. "The pistons 43 and 44 act oppositely to one another.

The valve 2 is provided with two pistons l5 and I6 connected by a rod l3. At the bottom part of the piston l6 there is a circular valve member I1 designed to cooperate with the seat l3 and when in contact with such seat closes the branch The distributor 4 for operating the valve 2 comprises a slide valve 23 which is L-shaped. The

position of slide valve 23 shown in Fig. 1 in full lines is the position it occupies when the valve 2 is in opened position. The dotted lines 2| show the position of the slide valve 23 when the valve 2 is moved to closing position. When the slide valve 23 is in the position shown in full lines the upper cylinder 22 of the watergate 2 is connected by the pipe 23, the aperture 24, and the aperture 25, through the exhaust pipe 26 to the atmosphere,

The lower cylinder 23 of the Watergate 2 is connected by the pipe 30 and the aperture 3| to the chamber 23 of the distributor 4 and thence by the pipe 32 and aperture 33 to the water main junction I. Therefore when the slide valve 23 is in the full line position the lower piston I3 is subjected to the pressure in the water main and is moved upwardly while the water in the cylinder 22 is exhausted through the pipe 23, aperture 24, aperture 25 and exhaust pipe 26.; On the other hand, when the slide valve'2ll is in the dotted line position, the piston I6 is subject to the pressure prevailing in the water mains through pipe 23, aperture 24, chamber 23, pipe 32 and aperture 33 and the cylinder 23 is exhausted through the pipe 33, aperture 3|, aperture 25 and exhaust pipe 26.

The means for releasing the slide valve 23 so that it may move from the right to the left in Fig. 1 and bring about the closing of the circular valve member l1 upon its seat I3 comprises a tooth 5 carried by a control rod 31. The tooth 5 cooperates with the hook 13 provided upon a pivoted trigger 36. The control rod 31 passes through a stufllng box 43 and a fixed abutment 33. Encircling the control rod 31 on the side of the abutment 33 opposite to that where the distributor 4 is located is the spring 6 having one end bearing against the abutment 33. The other end of the spring bears against a disc 33 fixed upon the control rod 31 and a handle 11 is provided upon the end of the control rod 31 for manual control of rod 31 and of the slide valve 23.

Means for operating the releasing means comprises the following: Two pistons 43 and 44 reciprocate respectively in cylinders 3 and II). The bottom of cylinder 3 is connected by a pipe 45 to the Pitot tube 46 located so as to be subject to the pressure in the branch 3. The upper portion of the cylinder 3 above the piston 43 communicates with the atmosphere. The lower portion of the cylinder III is connected by a pipe 5| to the down-stream Pitot tube 46.

It is to be understood that the expression down-stream and "up-stream mean in general the Pitot tubes respectively subjected to the lowest and highest pressure when the flow comes from the water main junction I. The pressure difference between the two Pitot tubes reverse when the flow reverses in branch 3.

The piston 44 in the cylinder I3 is operated by the pressure difference created by the Pitot tubes 46 and 53 submitted to the flow into branch 3. When the flow is from the water main junction l towards the branch 3 the piston 44 is subjected to a force which tends to move the piston 44 downwardly.

In such case the piston rod 56 exerts a pull upon the belt 51 which is wound on the pulley 58 and secured thereto at the point 53 (Fig. 1 and Fig. 4).

The piston rod 63 of the piston 43 also exerts a pull upon the belt 64 (Fig. l and Fig. 3) which is wound upon the pulley 65 and secured thereto at the point 66 (Fig. 3). The pulleys 56 and 55 are fixed to the same shaft 61 which is rotatably mounted. A gear 66 is also fixed on the shaft 61 which meshes with a toothed rack 63. The profiles of the pulleys 53 and 65 are preferably formed in accordance with a logarithmic law in order that the angular position of the gear 63 may be expressed in angles proportional to the logarithm of the ratio of the forces brought into play respectively on the pistons 43 and 44.

For example, if it is assumed that a force kip acts on the piston 43 and that a force of kzq acts on the piston 44 wherein p represents the pressure in the branch 3 and q the flow in such branch then the resultant angle assumed by the gear 68 will be:

1 k log? in which k1, kg and k3 are constants.

The term log 5 of liquid. The gear 68 as mentioned above represents the resistance of branch 3 to the flow meshes with the rack 69 and said rack is connected to the piston 8 reciprocating in the oil filled cylinder 1.

The cylinder 1 has, fixed to one end thereof. an operating rod 16 designed to cooperate with the trigger 36 for tripping the hook 18 from the tooth 5. The rod 16 is slidingly mounted on a fixed abutment l5 and on the side of the abutment "l5 opposite to trigger 36, the rod 16 is encircled by a spring 13 having one end bearing against the fixed abutment l5 and the other end bearing against a side wall of cylinder 1. Cylinder 1 is also slidingly supported by the support '14. A bypass 80 is provided in the cylinder 1, opposite ends of the cylinder 1 communicating together through bypass 88.

Whenever ratio varies at a high rate (p diminishing or q increasing and this together or not) the new balanced position of the pulleys 58 and 65 correspondsto a clockwise rotation of the gear 68 thereby moving the rack 69 from left to right as shown in Fig. 1. Since it is a high rate variation, piston 8 will thus move up cylinder 1 which is filled with oil or liquid of appropriate viscosity overcoming the action of the spring 13 and the rod 16 will trip the trigger 36 thereby permitting the spring 6 to bring the slide valve to the dotted line position whereby the valve 2 is closed. The releasing system may be reset by manually moving the rod 31 by the handle 11 against the action of the spring 6 and the hook 18 will then retain the tooth 5 holding the slide valve 20 in its right hand position of Fig. l and thereby again opening valve 2.

On the other hand, if the motion of the rack 69 is relatively slow oil will pass through the bypass 80 and the cylinder 1 will not follow the movements of the rack 69. In such case the trigger 36 is not tripped.

It is obvious that as the flow takes place from the branch 3 towards the water main junction point I the action of the pressure is not compensated by the action of such a flow because their effects are no more opposite one to another. On the contrary, if the flow reverses and as soon as such occurs the opposing action of the piston 44 will appear. This results in the advantage that the release of the distributor 4 cannot take place when the branch 3 discharges into the junction point I and this is a safety advantage because in the case of a breakage in the branch 3 it is advantageous to allow such branch to discharge into the junction point I as long as possible.

The device described above is suitable in the case of an isolated pipe wherein the pressure would not vary abruptly other than in the case of a rupture.

On the other hand, where there are adjacent mains such as 83, 84 and 85 wherein ruptures might occur with an abrupt lowering of pressure at the junction point I, the square of the flow, q, into the branch 3 because of the inertia, of the water will decrease less rapidly than the pressure so that the ratio will sharply vary even though the branch I is intact and the rod 16 will actuate the trigger 36.

In order to remedy any ill-timed releasing of that kind a cylinder 9, such as shown in Fig. 5, may be used. Piston 43 reciprocates in the cylinder 9 and piston 43 acts upon a spring 88 connecting the piston rod to the belt 64. Therefore, when the pressure p abruptly decreases due to a breakage in the adjacent mains 83, 84 or the piston 43 will not transmit pressure action quickly because of the retarding effect of the throttling faucet 89.

This retarding action takes place in the following manner:

The spring 88 connecting the rod of the piston 43 to the belt 64 allows the independent displacement of the piston 43 with relation to the piston 44 in such a way that the valve 89 acting so as to slow the variations of the position of the piston 43 delays the action upon the pulleys due to the pressure p in the conduit.

In this way the time constant of piston 43 is set approximately equal to the time constant of the flow into the branch 3 and the torque exerted by the belt 64 will constantly balance the torque exerted by the belt 51 on the shaft 61. Therefore, an ill-timed releasing is avoided since on account of the inertia of the water the term q cannot vary as fast as p. The time constant of piston 43 may be adjusted so as to be a little greater than that one of the flow into branch 3 without any inconvenience since the restoration of the mains to normal use generally takes place slowly.

In Fig. 2 there is shown another modification of the invention wherein the piston 43 actuated by the pressure p in the branch 3 is balanced by means of a coil spring 90. Also the piston 44 actuated by the Pitot tube II is balanced by a coil spring 9|. The rod 63 of the piston 43 has attached thereto a rope 64' that is wound on the pulley 65.

The pulley 65 is fixed to the rotatably mounted shaft 61". At the right hand end of the shaft 61" is fixed a bevel gear 93. The piston rod 58 of piston 44 has attached thereto a rope 51' that is wound upon the pulley 58 which in turn is also fixed to the shaft 61'. At the left hand end of shaft 61 as shown in Fig. 2 a bevel gear 92 is fixed. The respective shafts 61' and 61" are located in alignment with one another. A pair of bevel wheels 94 and '94 rotatably mounted upon a supporting member 68 mesh simultaneously with the bevel gears 92 and 93. a

A planet gear 95 is out in the circumference of the support 68 and meshing with such planet gear is a rack 69. The other elements such as the rack, piston 8 and cylinder 1 involved in this modification are the same as previously described with reference to the construction shown in Fig. l.

The operation of this modification is as follows. The gear assembly 92, 93, 94 and 95 constitute a differential. Therefore, the movement of rack 69 is proportional to the sum of the rotations of pulleys 58 and 65 and since these movementsof rotation are proportional to the respecaesaaea.

tive iogarithms of p, on' one hand, and of. q, on

the other hand, with the same proportional factoron both sides, the difference in such movements willbe proportional to the logarithm of From this it results that the position as is dependent upon theratio q with the device described a release is assured every time that oi the rack would thereby be diminished considerably, and the rod 16 would react with the trigger 36 "and bring about a shutting of the valve 2.

The faucet 39, therefore, will allow adjusting the time constant of the piston 43 so that it will be equal to the time constant of the square I of the flow into branch 3 or slightly larger.

" In this way, an unexpected closure caused by ruptures in the mains, 33, 34 or 85, is avoided. Such ruptures bring about a rapid decrease in pressure at the junction point I and an ill-timed closing of the automatic protecting valves on uninjured mains.

Instead of a cylinder movable along its axis use may be made of another trigger operating mechanism.

Referring to Fig. 6 the junction point of two water mains of a distribution network is shown at I. The automatic Watergate 2 permits cutting off branch 3. The distributor 4 controls the valve of the Watergate and the releasing elements are disclosed at 5, 6 and 36 as described heretofore. The cylinder I44 is submitted to the pressure existing in branch 3 upstream from the Watergate 2.

The automatic Watergate 2 comprises two pistons I5 and I6 which are interconnected by a rod I3. At the bottom portion the upper piston is provided with a valve I1 which when seated upon the seat I3; cuts the flow through the branch 3.

The distributor 4 which operates the watergate 2 comprises a hollow L-shaped slide valve 23. The full lines in Fig. 6 show the slide valve in its position when valve I1 is kept in open position. The dotted lines showing in Fig. 6, shown at 2|, indicate the position the slide valve holds when closing the valve 2.

When the slide valve is in the full line position ofFig. 6 the upper cylinder 22 of the watergate 2 communicates through the pipe 23, the aperture 24, the aperture 25 and thence through the exhaust pipe 26 to the atmosphere.

The lower cylinder 29 of the Watergate 2 communicates through pipe 33, aperture 3|, chamber 23 and pipe 32, aperture 33 with junction point I. As a result of such connections the valve member I1 is maintained away from its seat I3.

4 On the other hand, however, when the slide valve 23 is in the dotted line position 2I the lower cylinder 23 will communicate through pipe 33, aperture 3|, aperture 23 and pipe 23 to the atmosphere while the upper cylinder 22 will communicate through pipe 23, aperture 24, chamber 23, the pipe 32 and aperture 33 at the junction point I. When the slide valve 23 is in dotted line position thevalve member I1 is forced to closing position and maintained closed.

releasing system comprises a tooth Len-'- gaged by a trigger 33. having a hook 13. The tooth is provided on the control rod 31 which rod is ur'g'e'd towards the'right inFig. 6 by a spring 3 which has one end in contact with a disc 33 mounted upon rod 31 and the other end bearing against 'afi'xed abutment 33. The control rod ill-passes a stufilng box 43 and is ilxed to the slide valve 23. I

Wh'en the handle 11' is urged so as to tighten the spring 6, the releasing mechanism may be reset with the hook 13 engaging the tooth 3.

The system for actuating the trigger 33 comprises a differential manometer H and a pressure accumulator I44 which functions selectively. The manometer 4I comprises two chambers I33 and Ill and the membrane 42 separates the two chambers and rests against. a disc 41. The disc 41 is provided with a rod 43 which extends through the stufllng box 43 and is encircled by a return spring 52 which bears at one end upon a fixed abutment 33 and at the other end on a disc 33 iixed to the rod 43.

When the pressure acting upon the respective races of the membrane 42 results in a movement from right to'leit as seen in Fig. 6 the force of the spring 52 has been overcome and the end 33 of'the rod 43 contacts the trigger 33 and trees the releasing system. When the hook 13 is released the tooth 5 is free and the spring 3 moves the rod 31 toward the right as seen in Fig. 3 whereby the valve member I1 is moved to its seat I3. The pressure accumulator cylinder I44 is provided with a piston 33 whose right hand face as seen in Fig. 6 is open to the atmosphere and a return spring 3| bears at one end against the right hand face of the piston 33 and at the other end against the fixed abutment I32. The cylinder I is connected by a pipe 33 to the branch 3.

Whenever the pressure in the branch 3 falls water passes through the pipe 33 from the cylinder I44 due to the action of the piston 33, which is urged by spring 3|; and such action continues until a new balanced position-has been reached.

On the other hand, when the pressure increases in the branch 3 the water will enter the cylinder I44 slowly due to the throttling action at 1| which is adjustable by means ofthe pin screw I3. The clack valve 32 is closed at such time. The clack valve 32 is closed by action of the spring 12 which is of suitable softness. By the above described design any ill-timed releasing of the trigger 33 is avoided, such as:

1. When a flow is initiated in the branch 3 since at such time the pressure rises.

2. Whenever there is a rupture in an adjacent branch the automatic watergate therein having operated, the pressure then rises rapidly at junction point I.

By the action of the cylinder I44 the operation of the valve member I1 is selective in that it will prevent any closing of the valve when the water acceleration corresponds with a rise in pressure at I.

Also, a rise in pressure in the branch 3 will permit the upstream chamber of the manometer 4| to have a lower pressure than that existing at inlet 34 because of the time lag caused by adjustable throttling H.

The manometer 4| is connected on one hand by the pipe 8! to the cylinder I44 and on the other hand to the branch 3 by the pipe 82 connected at 34 so that the distance separating the junctions 34 and 35 of the pipes 82 and 86 with the branch 3 is sufiicient to secure a good sensitivity to acceleration of the releasing system.

The cylinder 144 may be replaced by a simple closed chamber 244, such as shown in Fig. '7, containing air; in order to avoid dissolution of air and elimination thereof, this air may be confined in a rubber bladder |4 provided with a fiat valve l9 such as used in bicycles or automobile tires extending outside of chamber 244.

In accordance with another modification of this invention a plate 41 has been mounted at the end of a rod 48, this rod 48 being provided with a small disc 54 on which acts a restoring spring 52 the other end of which lies on the support 53. A rubber foil 42 separates a casing into two compartments I09 and NH. A hollow rubber ball I4 is located in compartment I and might be refilled with air at will through the valve |9 protruding outwardly. At 62 is a clack-valve submitted to the action of spring 12; this clack-valve is by-passed through an adjustable throttling device needle valve 21. The pipe 86 transmits the pressure of the main 3 in the right hand side on chamber Hill. The pipe 96 transmits the pressure taken at the neck 91 of the Venturi pipe 98'to the left hand side chamber |0|. In this manner, if there is any sudden equal drop of pressure on 99 and 91 the ball I 4 increases in volume and the clack-valve releases water into the main 3 and conversely if pressure increases but water is stopped by clack-valve 62 there is an opposite action, the plate 41 being urged to right. Therefore when the main 3 again comes in action, the effect of acceleration of water which would otherwise push the plate 41 to the left will be overwhelmed by the faster flow of water, into the left hand side compartment |0| due to compression of air in the ball l4.

oppositely if there is a rupture in main 3 beyond point 91 an important drop of pressure between 9'| and 99 will take place which will not be compensated, this drop being mainly due at the beginning to acceleration of water in main 3 and magnified by a sufficient distance between points 9! and 99. This acceleration being transient, the

throttling effect at 91 prevails later if such transient acceleration should not move the rod. 51.

' Rod 48 acts on a trigger such as 36 (Fig. 1) releasing a tooth like which as before explained operates the closure of the main valve such as 2".

This last modification provides the use of a differential manometer that will govern the releasing of the machanism to bring about the closing-of an automatic Watergate when the water acceleration goes above a certain value. The differential manometer is connected to two spaced points of the branch to be protected so that the difference in pressure owing to acceleration alone being able to bring about releasing.

Conjointly, to the diiferential manometer there can be made use of a selective device consisting in means for preventing the release of the closing mechanism, when the pressure to the nearby extremity of the main stump is increasing, those 10 means being characterized notably by the use of a rubber chamber in communication with the upstream pressure intake canalization of the dif-.

fcrential manometer, this piping being fitted with a valve and a throttle bypass that permit the liquid to get out easily from this capacity, but not to enter as easily.

Finally as the pressure drop created concomitantly to the waters acceleration, might have only a transitory existance, one can furthermore conmeet the downstream intake of the release differential manometer on the downstream intake of a pressure drop generator such as venturi, tuyre or diaphragm so as to increase the safety in apparatus functioning.

The following are examples of operation of the invention in different cases:

In mains 3 (Fig. 1) in the vicinity of the auto matic valve 2, the quot ent of the pressure p by the square q of the rate of flow q measures the resistance of the main to the flow. If flow variesthrough normal service conditions, variations, in

rate of flow are slow. On the contrary a break in a main is followed by a rapid variation of resistance of the main and the controls of the automatic valve 2 are set up in closing position 4, through action of instrument l8, 5, 3i, the latter being driven in accordance with the time derivation of the quotient P /q When several mains are connected together (Fig. 6), it is desirable that when one of the mains breaks all the respective automatic valves do not close at the same time but that the uninjured mains continue to work. On this principle systems have been designed for delaying the effect of pressure variations. If a rapid decrease of pressure occurs in main 3, the rate of flow, by virtue of the water's inertia decreases slower than the pressure and the throttle 83 (Fig. 2) avoids a rapid flow of water from chamber 9 to main 3 and prevents the closing of the automatic valves.

If one water main is fed by a reservoir in which the level of water is at 60 meters altitude and a break occurs on the main, at 10 meters altitude and the main length between break. and reservoir is 5,000 meters; then at the spot of the break, pressure in the water main falls off to substantially zero. Water in the main is at once submitted to an acceleration which balances the pressure forces. Pressure drops in the upstream part of the main will be one centimeter water column per meter.

If the length of the main included between the two connection points 33 and 34 (Fig. 6) is 25 meters, a pressure drop of 25 centimeters water-.

column then surges on instrument 4|; 2. pres-. sure drop of such importance is largely sufficient for setting automatic valve control in closing operation.

If after main 3 has been closed, it is again setto normal service conditions; fiow in main 3 might increase too swiftly and the closing mech I 1 anism might enter in action.

" in the others.

Fig. 8 illustrates an installation comprising a chamber analogous to chamber 244 of Fig. '7 and a pressure drop generation system such as a Venturi pipe. This design combines additively the drop of pressure effects both of the acceleration and of the rate of flow.

It is advantageous with respect to Fig. 8 operating in such a manner that the distance between the point in the neighborhood of the connecting junction constructed upon the conduit 8 and the point located at the neck of the venturi should be at least equal to times the diameter of the conduit and preferably equal to 20 times such diameter.

What is claimed is:

1. In a valve located upon a liquid conduit, a water tight element whose application against an orifice and its recess assures respectively the opening and the closing of said valve, motor means for closing said water tight element, control means for said motor means, a chamber, a flexible membrane dividing said chamber into a first and a second compartment, a first pipe, one of the ends of said first pipe being tapped to a first point of said liquid conduit upstream while the other end is tapped to said first compartment of said chamber, a second pipe, one of the ends of said second pipe being tapped to the second compartment of said chamber and the other end being tapped to a second point of said conduit sufilciently spaced down stream from said first point in order to cause suddenly a difference in pressure between the two tapped points upon said conduit as a function of the second time derivative of the liquid volume which traverses a local cross-sectional area of said conduit, said difference in pressure tending to bring about a deformat ipn of said flexible membrane, means for opposing the deformation of said flexible membrane when said second time derivative does not exceed a predetermined value and for deforming said membrane when said predetermined value is exceeded, means operated by the displacement of said membrane to bring about the action of said control means, said motor means and said water tight element to close said valve when said flexible membrane is deformed simultaneously with a rupture in said conduit and means for preventing the closing action of said valve when the pressure in said conduit increases...

, 2..1n a valve located upon a liquid conduit, a water tight element whose application against an orifice and its recess assures respectively the opening and the closing of said valve, motor means for closing said water tight element, control means for said motor means, a chamber, a flexible membrane dividing saidchamber into a first and a second compartment, a movable plate bearing against said flexible membrane a first pipe, one of the ends of said first pipe being tapped to a first point of said liquid conduit upstream while the other end is tapped to said first compartment of said chamber, a second pipe, one of the ends of said second pipe being tapped to the second compartment of said chamber and the other end being tapped to a second point of said conduit sumciently spaced down stream from said first point in order to cause suddenly a difference in pressure between the two tapped points upon said conduit as a function of the second time derivative of the liquid volume which traverses a local cross-sectional area of said conduit, said difference in pressure tending to bring about a deformation of said flexible membrane, a spring cooperating with said plate for opposing'the determined value and for deforming said membrane when said predetermined value is exceeded,

means operated by the'displacement of said membrane to bring about the action of said control means, said motor means and said water tight element to close said valve when said flexible membrane is deformed simultaneously with a rupture in said conduit and means for preventing the closing action of said valve when the pressure in said conduit increases.

3. In a valve located upon a liquid conduit, a water tight element whose application against an orifice and its recess assures respectively the opening and the closing of said valve, motor means for closing said water tight element, control means for said motor means, a chamber, a flexible membrane dividing said chamber into a first and a second compartment, a movable plate bearing against said flexible membrane, a first pipe, one of the ends of said first pipe being tapped to a first point of said liquid conduit upstream while the other end is'tapped to said first compartment of said chamber, a second pipe,

one of the ends of said second pipe being tapped to the second compartment of said'chambr and the other end being tapped to a second point 0! said conduit sufilciently spaced down stream from said first point in order to cause suddenly adifference in pressure between the two tapped points upon said conduit as a function of the second time derivative of the liquid volume which trav-- erses a local cross-sectional area of'said conduit, said difference in pressure tending to bring about a deformation of said flexible membrane, a spring cooperating with said plate for opposing the deformation of said flexible membrane when said second time derivative does not exceed a predetermined value and for deforming said membrane when said predetermined value is exceeded, means operated by the displacement of said membrane to bring about the action of said con' trol means, said motor means and said water tight element to close said valve when said flexible membraneis deformed simultaneously with a rupture in said conduit, means for preventing the closing action of said valve when the pressure in said conduit increases, a trigger normally locking said control means of said motor means and a rod having one of its ends connected to said plate and the other end cooperating with said trigger to release said control means when said flexible membrane is deformed to bring about the action of said control means simultaneously with a rupture in said conduit.

4. In a valve located upon a liquid conduit; 0 water tight element whose application against an orifice and its recessassures respectively the opening and the closing of said valve, motor means for closing said water tight element, control means for said motor means, a chamber. a flexible membrane dividing said chamber into a first and a second compartment, a first pipe, one of the ends of said first pipe being tapped to a first point of said liquid conduit upstream while the other end is tapped to said first compartment of said chamber, a pipe, one of the ends of said second pipe being tapped to the second compartment of said chamber and the other end being tapped to a second point of said conduit sumciently spaced down stream from said first point in order to cause suddenly a difierence in pressure between the two tapped points upon said conduit as a function of the second time derivative of the liquid Volume which traverses a local cross-sectional area of said conduit, said difference in pressure tending to bring about a deformation of said flexible membrance, means for opposing the deformation of said flexible membrane when said second time derivative does not exceed a predetermined value and for deforming said membrane when said predetermined value is exceeded, means operated by thedisplacement of said membrane to bring about the action of said control means, said motor means and said water tight element to close said valve when said flexible membrane is deformed simultaneously with a rupture in said conduit, means for retarding the increase of pressure in said first compartment, said means comprising a retarding chamber having a volume variable with the pressure of the liquid in said first pipe, two branches connecting said last named chamber to said conduit, a neck provided in one of said branches, a valve provided in the otherbranch to retard the transmission of the pressure from the sampling point upstream to said first compartment of said first named chamber to prevent the deformation of said flexible membrane and its closing action when the pressure in said conduit increases.

LOUIS CHARLES EUGENE FRAGER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,309,808 Pfau July 15, 1919 1,514,839 Edwards Nov. 11, 1924 2,072,314 Rhodes Mar. 2, 1937 2,081,542 Kidney May 25, 1937 2,137,874 Goldberg Nov. 22, 1938 2,302,370 Hedene Nov. 17, 1942 2,381,447 Hedene Aug. 7, 1945 

